Behemoth notes (part 4) are dropped by the Runebound behemoth. The drop is random, just like all other Dungeoneering journals. The notes describe the instability of the behemoth race, often wasting resources on them to attempt taming them. Should they become a major problem, the behemoths are herded back to their home plane. The author describes an "elegant but expensive" method of taming the behemoths - runebinding. This process involves infusing a behemoth with magic, then controlling magical pulses through a number of pillars. It was mentioned Lexicus Runewright came up with the idea.

Transcript

The behemoths have never been a stable race, or particularly predictable. They may be useful, but their influences and actions have meant losing two years of digging through cave-ins and countless resources being spent on taming them, often with no luck. Our problems stem from them being near-impossible to kill or herd back through their portals should they become unruly. Once they are here, they are here permanently it seems. Runebinding is the elegant but expensive solution, whereby a behemoth is infused with rune magic and then controlled by magical pulses through a series of pillars. Lexicus came up with the system, before his mind wandered, and we haven't been able to improve on it since.